With the rapid development of display technology, touch screen panels have become popular in people's life. At present, a conventional in-cell capacitive touch display is achieved by adding touch scanning lines and touch sensing lines on a conventional Thin Film Transistor (TFT) array substrate. That is, two layers of strip electrodes are formed on a surface of the TFT array substrate, the strip electrodes in one layer intersecting with the strip electrodes in the other layer. The strip electrodes in one layer and the strip electrodes in the other layer respectively serve as the touch driving lines and the touch sensing lines of the touch display, and mutual capacitances are formed at positions where the strip electrodes in one layer intersect the strip electrodes in the other layer. An operation procedure of the above conventional capacitive touch display is given as follows. When touch driving signals are applied to electrodes serving as touch driving lines, voltage signals in the touch sensing lines generated through the mutual capacitances may be detected. Here, if the touch screen is in contact with a human body, an electric field of the human body may affect the mutual capacitances and change the capacitance value of the mutual capacitances; hence, the voltage signals in the touch sensing lines generated through the mutual capacitances are changed. A touch position may be determined based on variations of the voltage signals. Conventional, two schemes are generally adapted to transmit a touch signal. In a first scheme, conductive golden balls are provided between an upper substrate and a lower substrate as a medium for transmitting the signal between the upper substrate and the lower substrate. In the case that a touch occurs in a display region, the touch signal is transmitted from the touch position to a periphery region, and then the touch signal is transmitted to the lower substrate via the conductive golden balls. In a second scheme, a set of Flexible Printed Circuits (FPCs) are additionally provided for the touch substrate. The FPCs may independently identify the touch signal.
With the progress of technology and the increased requirements of customers, many disadvantages of the above structure of the touch display device are obvious. Specifically, for the first scheme, the process capability of the conductive golden ball is poor, and there are many problems, for example, in coating the golden balls and in metallic contact between the golden balls and the substrates, thereby affecting product yield. Furthermore, in the case that the conductive golden balls are used as the medium for transmitting the signal between the upper substrate and the lower substrate, borders of the touch display device may not be narrowed due to poor alignment accuracy. Additionally, a distance between the upper substrate and the lower substrate may not be reduced due to the usage of the conductive golden balls. The second scheme may inevitably increase the cost due to the addition of the FPCs.